1985 Toyota pickup problem

i had the same exact happening with my 85 4runner the heater fan(turning on) was making the truck die while driving .. if i turned it off it would come back on .. i found that all my problem was, was the negative / ground off the battery was bad .. i wire brused where it conn. to the block / cleaned terminals and replaced the ground wire and now it werks fine .. hope it helps

Thanks for the reply, I checked all of the ground and positive wires took them off and cleaned them and it still does it. Had a guy tell me to start at the Fan switch inside the truck and trace it to the blower motor to see if it's grounded somewhere. Hopefully I will find it there.

i'm having a very similar problem, what did you find was the problem mtnmikem?

I still haven't found the root of the problem. I think I have a grounded wire somewhere.

my 85 pickup problem: would always start in the morning while motor was cold. After warmup, may not restart until cooled off, lifting hood helped. There was no spark coming out of ignitor coil. It got to point it would die while driving but would always restart after a break. Heater fan would work or not at it's own option. Turned out the distributor pickup coil was going bad. To check; use ohm meter on pink and white wires coming from distributor at large green connector clipped to motor right above distibutor. check for 140 to 180 ohms on the dist side of connector. my would be fine while cold, then run up to 450 or show open circuit. Replaced and motor starting/running problem solved. Heater fan issue is still with me as it was not related. Bad fan motor brushes? anyway good luck with yours.

Thanks man, I will give that a try.

my 85 pick up fan intermittent problem was the fan motor brushes need replaced.(365456 miles, first fan motor repair)